This study has been ongoing since 1992 when anti-HCV screening of blood donors was first introduced. The findings to date are in the final stage of preparation for submission to NEJM. The major findings are as follows: (comparisons are with controls who tested anti-HCV by EIA, but were negative on the RIBA specificity assay): (I) Characteristics of HCV infected donors as compared to controls were younger age, African-American race, lower education level and a more frequent history of liver dysfunction or sexually transmitted disease; (2) Risk factors that were independently associated with HCV infection were histories of transfusion, sexual promiscuity, intravenous drug use (IVDU), cocaine snorting and ear piercing in males; (3) Surprisingly, 41% of volunteer blood donors gave a history of IVDU; (4) HCV RNA was present in 86%, confirming that most anti-HCV positive individuals are chronic carriers, but raising the possibility that approximately 15% recover from this infection; (5) There was no evidence for sexual transmission of HC when specific partners were tested; (6) Among 77 anti-HCV positive subjects: 92% had histological evidence of chronic hepatitis and/or cirrhosis. (7) RIBA indeterminates were indistinguishable from RIBA negatives.